1. Field of the Invention
This invention relates to color television receivers, and more particularly, to a double-scanning non-interlace color television receiver which provides a high resolution picture on a large screen.
2. Description of the Prior Art
As the size of a picture screen of a television receiver is increased, the distance between the scanning lines increases, so that the resolution of the picture displayed thereon decreases. One proposed solution to avoid a decrease in resolution in such cases is to display the picture from a conventional television signal, which is formed of two interlaced fields of scanning lines, on a non-interlace double-scanning television system which scans every line twice. For example, each field of 262.5 scanning lines of the NTSC television system can be converted into a single frame having 525 consecutively scanned lines.
One problem with a non-interlace television receiver is the determination of the content of the scanning lines which are to be interpolated between the alternate scanning lines of the interlace television signal. The least expensive and simplest solution is to scan each line twice.
However, flicker is a serious problem in a double-scanning television receiver in which alternate lines are repeated for display. Flicker occurs when a point on a line is scanned at one brightness level in the first field and is then scanned at another, different brightness level in the second field. For example, if a point on the first scanning is dark, while the same point on the second scanning is light, flicker occurs. Flickering of the picture is objectionable and must be eliminated to achieve a high quality television picture.